Hydrostatic-set open hole packer with electric, hydraulic and/or optical feed throughs

ABSTRACT

Devices and methods are described for disposing electric, hydraulic and/or optical cables or conduits axially through a hydrostatically-set packer mechanism. Radial fluid communication is also provided through the inner mandrel so that the packer mechanism may be set using hydrostatic pressure within the flowbore. Feed-through paths for the cables or conduits isolate the cables/conduits from fluid pressure as well as axial or torsional tensile forces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the design of downhole packers and tomechanisms for passing cables and conduits through a packer. Inparticular aspects, the invention relates to the design of packers thatare set using hydrostatic wellbore fluid pressure.

2. Description of the Related Art

When installing a production string within a wellbore, it is oftennecessary to form a fluid seal within a large diameter opening, such asan open (uncased) hole. To accomplish this, a packer assembly is neededthat can provide large radial expansion of the sealing element.Unfortunately, conventional large expansion packer systems generallylack the ability to pass electrical or fiber optic cables or fluidconduits axially through the packer assembly so that other devices maybe used below the packer device.

The desirable requirements for a large diameter packer system aretypically at odds with those for a conduit pass-through system. U.S.Pat. No. 6,220,362, issued to Roth et al. describes a pass-throughconduit arrangement for a packer assembly or other tool. The Roth patentis owned by the assignee of the present invention and is incorporatedherein by reference. Roth describes a system wherein one or more axialconduit passages are formed through an interior portion of a packer orother tool. Roth teaches that there be complete pressure isolationbetween the conduit and both the tubing and the annulus. However, Rothdescribes the use of a separate carrier 60 that lies radially within thetool mandrel 24 and is used to define the longitudinal passages for theconduits or cables. The potential exists for improper sealing betweenthe carrier and mandrel during fabrication of the tool, leading toundesirable fluid entry into the longitudinal passages. Additionally,this design does not offer any means for radial communication of fluidoutwardly from the flowbore of the tool to the radial exterior of thetool. In fact, the requirement that the longitudinal passages remainisolated from fluid pressure from the flowbore, as well as the annulus,dictates against penetration of the carrier and/or mandrel by a radialfluid communication passage. If the carrier and mandrel of this toolwere perforated to allow radial fluid communication, the passagesdefined therebetween would undesirably become exposed to externalwellbore fluid pressures.

To the inventor's knowledge, conduit feed through systems have not beensuccessfully integrated into hydrostatically-set packer assemblies. Itis believed that this failure is due to the complexity of a hydrostaticsetting mechanism and the need for such a device to communicatehydrostatic fluid pressure through the inner mandrel of the packerassembly and into a chamber within the exterior portion of the packerassembly. The use of multiple interior pieces, such as a separatecarrier and mandrel, to define a longitudinal cable/conduitpass-through, and the attendant assembly requirements, also adds to thedifficulty of incorporating a cable feed-through feature into ahydrostatically-set device.

U.S. Pat. No. 6,842,315 issued to Coronado et al., describes ahydrostatically-set packer device having a composite sealing elementwith large radial expansion capabilities for use in through tubing andopen hole applications. This patent is owned by the assignee of thepresent invention and is, therefore, incorporated by reference. Thedevice of the '315 patent provides no feed-through arrangement forcables or conduits to be passed longitudinally through the packerdevice.

The present invention addresses the problems of the prior art.

SUMMARY OF THE INVENTION

The invention provides devices and methods for axially disposingelectric, hydraulic and/or optical cables or conduits through the innermandrel of a hydrostatically-set packer mechanism. In accordance withthe devices and methods of the present invention, radial fluidcommunication is also provided through the inner mandrel so that thepacker mechanism may be set using hydrostatic pressure within theflowbore. The axial feed-through path(s) for the cables or conduits areisolated from flowbore and annular fluid pressure. Additionally, thecables/conduits are protected from axial tensile forces and torsionalforces that might damage them.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C present a side, cross-sectional view of an exemplary packerassembly with conduit feed through system constructed in accordance withthe present invention.

FIG. 2 is an axial cross-section taken along lines 2-2 in FIG. 1C.

FIG. 3 is an axial cross-section taken along lines 3-3 in FIG. 1C.

FIGS. 4A-4C present a side, cross-sectional view of the packer assemblyshown in FIGS. 1A-1C, now with the packer element having been set.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1A-1C, 2, and 3 illustrate an exemplary hydrostatically-set packerassembly 10 that is constructed in accordance with the presentinvention. The packer assembly 10 includes a central mandrel 12 havingan upper threaded end 14 which allows the packer assembly 10 to beincorporated into a production tubing string. The central mandrel 12defines a central axial flowbore 16 along its length. A cable feedthrough path, generally designated as 18, passes through the centralmandrel 12. Beginning at the upper end of the packer assembly 10, thecentral mandrel 12 features a radially enlarged upper portion 20 withouter threads 22. Below the enlarged upper portion 20 is a radiallyreduced mandrel portion 24. At the lower end of the radially reducedportion 24 is a lower radially enlarged portion 26. The enlarged portion26 also defines an enlarged bore portion 27 within. The lower portion 26presents an outwardly projecting shoulder 28 and a threaded connection30 to a lower end sub 32. The lower end sub 32 includes a set ofinterfitting longitudinal anti-rotation splines 34 and an axial cablepassage 36. The splines 34 engage complimentary splines 35 formed on theoutside of the central mandrel 12. Below the cable passage 36 is alateral cable opening 38.

In a currently preferred embodiment, the feed-though path 18 includes anaxially-oriented longitudinal central portion 40 and an upper angled endportion 42 that extends from the upper end of the central portion 40radially outwardly to an axial upper end passage 44. The axial upper endpassage 44 includes an enlarged bore 46 that is shaped and sized toaccommodate end nut 48. The lower end of the central portion 40interconnects to a lower angled end portion 50 that extends radiallyoutwardly to an axially-oriented lower portion 52. The lower end of thelower portion 52 also has an enlarged bore 54 that is shaped and sizedto accommodate an end nut 56. It is noted that the feed-through path 18,and all of its individual components 40, 42, 50, 52, are preferablyconstructed by drilling of suitably sized holes or passages through thecentral mandrel 12. The component portions 40, 42, 50, 52 shouldinterconnect with one another axially to provide a continuous path. Anexemplary cable 58 is shown disposed within the feed-through path 18 andsecured therewithin by end nuts 48, 56. It can be seen that a portion 60of the cable 58 extends upwardly toward the entry of the wellbore (notshown) while another portion 62 of the cable 58 extends downwardlytoward a location below the packer assembly 10. Thus, the cablefeed-through path 18 allows communication through the packer assembly 10to a device (not shown) that is located below the packer assembly 10. Itis noted that the term “cable,” is used herein to refer to an electricalcable, a hydraulic fluid conduit, a fiber optic cable, or any other typeof tubular structure that is used to transmit fluid, power orcommunications into or out of a wellbore.

The enlarged bore portion 27 of the central mandrel 12 accommodates anactuating sleeve 62 and an internal guide sleeve 64. The guide sleeve 64provides a radially exterior surface 66 that defines the inner boundaryof the lateral cable opening 38. Additionally, the guide sleeve 64presents an inner surface 68 with an upper radially is enlarged boreportion 70. The actuating sleeve 62 presents an inner surface 72 thatextends radially inwardly of the enlarged bore 70, thereby creating anengagement shoulder 74 at the lower end of the sleeve 62. The outerradial surface 76 of the actuating sleeve 62 carries a number of annularfluid seals 78, a dog recess 80 and a locking ring 79. It is noted thatthe actuating sleeve 62 is axially moveable between a lower position,shown in FIG. 1, wherein the lower end of the sleeve 62 contacts theguide sleeve 64, and an upper position, shown in FIG. 2, wherein theupper end 82 of the actuating sleeve 62 contacts an internal stopshoulder 84 of the central mandrel 12. Frangible shear screws 82 passthrough the body of the central mandrel 12 and into the actuating sleeve62 to initially secure the actuating sleeve 62 in its lower position.

A plurality of radial fluid communication ports 88 also pass through thecentral mandrel 12 to provide fluid communication between the internalflowbore 16 of the mandrel 12 and its radial exterior. As FIG. 2illustrates, the shear screws 82 are angularly offset from each of thefluid ports 88 about the circumference of the central mandrel 12. Fluidflow through the fluid ports 88 is initially blocked by the presence ofthe actuating sleeve 62 and fluid seals 78.

Beginning once again proximate the upper end of the packer assembly 10,a second set of longitudinal anti-rotation splines 90 are defined uponthe central mandrel body 12. Splines 90 interfit with complimentaryanti-rotation splines 92 on the central mandrel 12. The interfitting ofthe splines 90, 92 prevents rotation of the central mandrel 12components with respect to one another.

The ring 98 is retained in place upon the outer surface of the centralmandrel 12 by a housing sub 100 that is secured to the central mandrel12 by threaded connection 22. An annular space 102 is defined betweenthe lower end of the housing sub 100 and the outer surface of thecentral mandrel 12. Ring 104 is secured to the lower end of the housingsub 100 at threaded connection 106. The ring 104 provides tensioningportions 105, of a type known in the art, for exerting a tensioningforce upon the packer element 110.

An upper end setting sleeve 108 also surrounds the central mandrel 12below the ring 104. The setting sleeve 108 is used to help set thepacker element 110 that lies immediately below it on the radial exteriorof the central mandrel 12. During setting of the packer assembly 10, theupper end setting sleeve 108 remains stationary with respect to thecentral mandrel 12. The upper end setting sleeve 108 has a retainerportion 112 that extends over a portion of the packer element 110. Alower end setting sleeve 114 is located at the lower end of the packerelement 110 and also presents a retainer portion 116 that extends over aportion of the packer element 110.

The packer element 110 is preferably a composite packer element asdescribed in U.S. Pat. No. 6,843,315, issued to Coronado et al. Thispatent is owned by the assignee of the present invention and is hereinincorporated by reference. This type of packer element is suitable foruse in creating a fluid seal in larger bores and even uncased boreholesections. Below the lower end setting sleeve 114 is a setting, oractuating, assembly, generally shown at 118, having an upper sub 120with fluid fill port 122, a setting assembly housing 124 and a lower sub126. The setting assembly housing 124 encases an atmospheric chamber128. The atmospheric chamber 128 is bounded at axial ends by the upperand lower subs 120, 126. When the piston assembly 10 is in the unsetposition (shown in FIG. 1), the atmospheric chamber 128 is atatmospheric pressure.

An actuating piston, generally shown at 130, is retained within theatmospheric chamber 128. The actuating piston 130 is made up of a lowerpiston ring 132, central ring 134, and an upper piston ring 136, thesecomponents being affixed to one another by threaded connections 138,140. The lower piston ring 132 presents a fluid pressure receiving area142. Additionally, the lower piston ring 132 has an annular dog recess144 inscribed upon its inner surface. Elastomeric O-ring seals 146 areused to provide fluid sealing between the actuating piston 130 and thechamber 128. The upper end of the upper piston ring 136 is secured bythreaded connection 148 to a body lock ring assembly 150. The body lockring assembly 150 includes a locking ring 152 with an inner ratchetsurface 154. The ratchet surface 154 is formed to interengage withoutwardly-facing ratchet surface 156 on central mandrel 12. Packerelement setting member 158 is affixed to the body lock ring assembly 150and presents an enlarged setting portion 160 that abuts the lower end ofthe packer element 110.

A locking dog 162 initially secures the actuating piston 130 and thecentral mandrel 12 together. In the unset position, shown in FIG. 1, thedog 162 resides within a dog passage 164 that is disposed radiallythrough the central mandrel 12. A portion of the dog 162 extendsoutwardly into dog recess 144 in the actuating piston 130. Movement ofthe dog 162 radially inwardly is blocked by the presence of actuatingsleeve 62. It is noted that the dog 162 and all shear screws 82 areradially offset from the cable feed-through path(s) 18 so that thefeed-through path(s) 18 remain unexposed to fluid ingress and wellborepressures. This arrangement is best shown in FIGS. 2 and 3.

Hydrostatic forces are used to set the packer device 10. FIGS. 4A-4Cshow the packer device 10 in a set condition. When it is desired to setthe packer assembly 10, a shifting tool (not shown), of a type known inthe art, is disposed into the flowbore 16 of the central mandrel 12. Theshifting tool contacts the engagement shoulder 74 of the actuatingsleeve 62 and moves the actuating sleeve 62 axially upwardly. Thismovement will shear the shear screws 82 and unblock fluid communicationports 88. The locking ring 79 secures into a mating recess in thecentral mandrel 12 (see FIG. 4C) to secure the actuating sleeve 62 inthe upward position. Additionally, upward movement of the actuatingsleeve 62 will bring the dog recess 80 into general alignment with thelocking dog 162. The dog 162 is moved radially inwardly to residepartially within the recess 80 and is thus moved out of the outer dogrecess 144. This unlocks the actuating piston 130 from engagement withthe central mandrel 12. As upward movement of the actuating sleeve 62unblocks the fluid ports 88, hydrostatic fluid pressure present withinthe flowbore 16 will then be transmitted through the ports 88 and enterthe pressure receiving area 142. Wellbore hydrostatic pressure will bearupon the pressure receiving area 142 of the actuation piston 130 andurge the piston 130 axially upwardly. The packer element setting member158 will compress the packer element 110 axially to cause it to expandradially and become set.

It can be seen that the arrangement of the present invention provides ameans for disposing one or more cables axially through ahydrostatically-set packer device while also permitting radial fluidcommunication through the central mandrel. The feed-through paths 18 ofthe packer assembly 10 desirably isolate the cables from fluid pressurepresent in either the flowbore 16 or the annulus surrounding the packerdevice 10. Because the feed-through paths 18 are angularly offset fromthe fluid communication ports 88 about the circumference of the centralmandrel 12, fluid pressure being communicated radially through themandrel 12 will not enter the feed-through paths 18.

Cables extending through the feed-through paths 18 are also protectedfrom axial tensional forces that would be exerted upon the packerassembly 10 as it is being used as well as torsional forces that mightbe experienced as the packer assembly 10 is being made up or run in thewell. The cables are retained in place within the feed-through path(s)18 by end nuts 48, 56, which secure them to the central mandrel 12.

Those of skill in the art will recognize that numerous modifications andchanges may be made to the exemplary designs and embodiments describedherein and that the invention is limited only by the claims that followand any equivalents thereof.

1. A packer assembly for creating a fluid seal within a wellbore comprising: a tubular central mandrel having an upper end and a lower end, defining a central flowbore and having an outer radial surface; a packer element surrounding the tubular mandrel, the packer element being moveable between a radially reduced unset position and a radially expanded set position; a hydrostatic setting assembly for selectively causing the packer element to be set in its expanded position, the hydrostatic setting assembly comprising: a) a radial fluid communication port for communicating hydraulic fluid pressure within the central flowbore through the tubular mandrel to its outer radial surface; b) a piston element for receiving fluid pressure from the central flowbore and applying said fluid pressure to urge the packer element toward its set position; and a cable feed-through path defined within the tubular mandrel to allow a cable to pass from the upper end of the mandrel to the lower end of the mandrel.
 2. The packer assembly of claim 1 wherein the cable feed-through path comprises a longitudinal drilled hole in the mandrel.
 3. The packer assembly of claim 1 wherein the setting piston is releasably secured to the central mandrel by a locking dog.
 4. The packer assembly of claim 1 wherein the fluid communication port is angularly offset from the feed-through path about the circumference of the central mandrel.
 5. The packer assembly of claim 1 wherein the setting assembly further comprises an actuating sleeve that lies within the central flowbore and is moveable between a first position, wherein fluid communication through the radial fluid communication port is blocked, and a second position, wherein the actuating sleeve does not block the port.
 6. The packer assembly of claim 5 wherein the actuating sleeve presents an engagement shoulder that is shaped and sized to be contacted by a suitable shifting tool for movement of the actuating sleeve from its first to its second position.
 7. The packer assembly of claim 5 wherein: the setting piston is releasably secured to the central mandrel by a locking dog; and wherein movement of the actuating sleeve from the first to the second position releases the setting piston from the central mandrel.
 8. The packer assembly of claim 1 wherein the packer element comprises a composite packer element for use in creating a fluid seal within an uncased borehole.
 9. A system for disposing a cable axially through a packer device that is set hydrostatically, the system comprising: a central tubular mandrel defining a flowbore to contain hydrostatic pressure; a packer element carried by the central mandrel, the packer element being moveable between an unset position and an axially compressed set position; a setting mechanism for moving the packer element to its set position in response to hydrostatic pressure within the flowbore; and a feed-through path defined axially through the mandrel, the feed-through path retaining a cable in isolation from external fluid pressures.
 10. The system of claim 9 further comprising: a radial fluid communication port for transmitting hydrostatic fluid pressure from the flowbore to an actuation chamber located radially outside of the central mandrel; and wherein the fluid communication port is angularly offset from the feed-through path about the circumference of the central mandrel.
 11. The system of claim 9 wherein the feed-through path comprises a longitudinal drilled hole in the central mandrel.
 12. The system of claim 10 wherein the setting mechanism further comprises a piston element retained within the actuation chamber for receiving fluid pressure from the central flowbore and applying said fluid pressure to urge the packer element toward its set position.
 13. The system of claim 12 wherein the piston element is releasably secured to the central mandrel.
 14. The system of claim 13 wherein the piston element is releasably secured to the central mandrel by a locking dog.
 15. The system of claim 9 wherein the setting mechanism further comprises an actuating sleeve that lies within the flowbore and is moveable between a first position, wherein fluid communication through the radial fluid communication port is blocked, and a second position, wherein the actuating sleeve does not block the port.
 16. The system of claim 15 wherein the actuating sleeve is releasably retained in the first position by a shear pin.
 17. A method of disposing a cable axially through a hydrostatically-set packer device, the method comprising the steps of: forming a cable pass-through path within a central mandrel of the packer device; disposing a cable along the cable pass-through path; and securing an end nut upon the cable to secure the cable to the central mandrel.
 18. The method of claim 17 wherein the step of forming a pass-through path within the central mandrel comprises drilling a longitudinal hole within the central mandrel that is shaped and sized to accommodate the cable. 